The major objective of this study is to develop a comprehensive understanding of the keratinization process in order to more fully understand the numerous disorders which involve epidermis, hair, and nail. Since the fibrous proteins play a key role in the keratinized tissue of man, it is essential to obtain detailed information on them. We plan to study the changes in the fibrous protein in psoriatic epidermis during development and regression of lesions. This will be compared to hyperplasia induced in normal epidermis. Studies on the purification of an enzyme which converts peptide-bound arginine to peptide-bound citrulline will be continued. We plan to look for synthetic substrates which may be used as an assay. We shall prepare an antibody to human hair matrix proteins which may allow us to distinguish the various components which are present. This may be useful in genetic studies as well as in disease states. We shall continue our studies of epidermal cell cultures to understand the type of differentiation that occurs to see if the technique is applicable to studying disease. We shall examine the fibrous polypeptides and how the keratin molecule is put together, as well as certain characteristic enzymes such as histidine deaminase. We shall continue to study and collect inherited disorders of keratinization so that patient material will be available for laboratory study. We shall also expand our studies of synthetic retinoids on an number of inherited disorders of keratinization, including psoriasis.